Lancing device
A lancing device comprising a movable parallelogram-shaped rack. The rack rotates a linearly fixed pinion which drives a slider-crank system. The slider-crank system in turn drives a lance holder. The parallelogram-shaped rack defines one or more predetermined paths along which the pinion moves. The lance holder is prevented from being extended beyond a predetermined depth when the pinion reaches a predetermined position along the one or more predetermined paths. The pinion is mechanically stopped from further progress by intersecting two legs of the parallelogram-shaped rack. Teeth of the rack may be modified to reduce the chance the pinion may jam in the rack.
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This application claims the benefit of U.S. provisional applicatian 60/418,422, filed on Oct. 15, 2002, which is hereby incorporated by reference in its entirety.
FIELD OF THE INVENTIONThe present invention relates generally to blood monitoring devices, and more particularly, to a lancing mechanism, or lancing device, for lancing a patient's skin to obtain a sample of blood for analysis.
BACKGROUND OF THE INVENTIONIt is often necessary to quickly obtain a sample of blood and perform an analysis of the blood sample. Preferably obtaining the blood is as painless as possible. One example in which there is a need for painlessly obtaining a sample of blood is in connection with a blood glucose monitoring system where a user must frequently use the system to monitor the user's blood glucose level.
One method of monitoring a person's blood glucose level is by portable handheld blood glucose testing device. The portable nature of these devices enables the user to conveniently test his blood glucose levels wherever the user may be. To check the blood glucose level, a drop of blood is obtained from him, for example, from the fingertip using a separate lancing device. The lancing device contains a lance or lancet to puncture the skin. Once the requisite amount of blood is produced on the fingertip, the blood is harvested using the blood glucose-testing device. The blood is drawn inside the testing device, which then determines the concentration of glucose in the blood. The results of the test are communicated to the user by a display on the testing device.
Many prior art lancing devices use a spring directly coupled to the lance to move the lance to its penetration depth. The lance is drawn back to compress the spring. When released, the spring extends, thus forwardly propelling the lance to its penetration depth. More detail concerning lancing devices is set forth in U.S. Pat. No. 6,152,942, which is commonly assigned and incorporated herein by reference in its entirety. One problem associated with other prior lancing devices is that the penetration depth of the lance is dependent on a spring constant, which is a measure of the spring stiffness. The mechanical quality of the spring, including the stiffness, tend to vary, and in particular degrade, over time with use. Accordingly, over time, the penetration depth of prior art lances may vary. When the penetration depth of the lance lessens over time, the lance may not produce a laceration deep enough to draw the requisite volume of blood necessary for blood glucose analysis. Insufficient lancing can result in erroneous analysis if the user does not recognize that the lancing has not produced the requisite volume of blood for analysis. And if the user does recognize an insufficient lancing has incurred the user must re-lance resulting in another laceration in the user's skin and more pain. The user may eventually have to replace the lance, or the entire device because the accuracy and consistency of the laceration has degraded.
Another related problem associated with many prior art lancing devices is that when the spring forwardly advances the lance to its penetration depth, the spring extends past its static length. The spring then retracts the lance. But due to the oscillary nature of the spring, the lance is retracted past its static retraction position. If the lance continues to oscillate in this manner, it may repeatedly enter the laceration and penetrate the user's skin several times. With each actuation of such an oscillating lance, the user's skin is lanced several times which results in a larger laceration. A larger laceration in the user's skin translates into more pain for the user and a longer time for the laceration to heal.
Other problems associated with prior art lancing device include vibration and chatter of the lance during the lancing process. The vibration and chatter result in uncontrolled movement of the lance. Such uncontrolled movement may result in larger as well as more jagged lacerations. Another detrimental result is inaccurate punctures in the skin, with respect to both location and depth of the puncture.
Accordingly there is a need for continued improvement in lancing devices and glucose monitoring systems generally.
SUMMARY OF THE INVENTIONA lancing device according to the invention comprises a movable parallelogram-shaped rack. The rack rotates a linearly fixed pinion. The pinion drives a slider-crank system that comprises a drive wheel and a drive arm. The terms lance and lancet are used interchangeably herein. The drive arm in turn moves a lance holder which is supported to move in a linear path of motion. The pinion may be integral with the drive wheel, wherein the drive arm is connected directly to the pinion.
The parallelogram-shaped rack comprises a pair of acute angles and a pair of oblique angles. In the illustrated embodiment, the acute angle, which is furthest from the lance, but closest to the spring is referred to as the proximal acute angle and the other angle (located furthest from the spring) is referred to herein as the distal acute angle.
When the rack is in a cocked position the pinion is positioned proximate to the distal acute angle and a spring is compressed to apply a force in the direction of extending the lance. Upon releasing the rack, with a fulcrum or trigger, for example, the spring forces the rack downward such that the pinion rotates along as a first rack segment of the rack and then intersects the first oblique angle. The pinion then follows a second rack segment to the proximal acute angle.
The pinion being positioned at the proximal acute angle is also referred to herein as the fired position of the rack, or simply the fired position. For some applications, the oblique angles are 45 degrees; other angles will be determined according to the particular applications. In particular applications, the pinion rotates 180 degrees as it travels along the first and second rack segment from a cocked position to the fired position. The cocked position corresponds to the pinion being at the distal acute angle. Pulling the rack back in the opposite direction by a cocking force moves the pinion along third and fourth rack segments from the fired position to the cocked position.
A modified rack allows for a complete 360 degree rotation of the pinion as the rack moves through one cycle, e.g., from a cocked position to a fired position and back to a cocked position, without jamming the pinion. For many applications it is desirable that the rack is always in contact with the pinion, thus the exact position of the pinion relative to the rack may be determined. The rack is modified at both acute angles to reduce the possibility of the pinion becoming jammed in either of the acute angles. In one embodiment at least two teeth on each rack segment, for example, the two teeth on each segment positioned closest to each acute angle, are modified to create wider gaps between teeth. In the particular illustrated embodiment, both gap walls (the tooth portion that forms the gap) of each of the two teeth further from the acute angle corners are opened wider, while the gap walls closer to the corners of the acute angle are maintained in their conventional shape.
A guide pin and guide track combination may be used to guide the rack relative to a fixed plate. The term “plate” is used to generally refer to any relatively fixed structure. For example, the web of a housing of a portable lance may be referred to as a plate, in this context. The guide pin may be located, e.g., in a fixed position relative to the rack while the guide track is located in a fixed position on the fixed plate. For some applications, the guide track is a parallelogram and the pin is a parallelogram. Other pin and track combinations and shapes will be apparent to those of ordinary skill in the art. For example, the pin may be a typical cylindrical protrusion from a frame supporting the parallelogram-shaped rack. Alternatively, the pin may extend from the plate, for example.
The invention overcomes problems associated with the prior art and satisfies a variety of objectives.
OBJECT OF THE INVENTIONAn object of the invention is to provide an improved glucose-monitoring device.
Another object of the invention is to provide an improved lancing device.
Another object is to precisely control depth penetration and puncture location of a lance.
Another object is to prevent multiple inadvertent punctures.
Another object is to reduce lance vibration and chatter.
Another object is to provide a lance that repeatedly penetrates to a consistent depth over the lifetime of an apparatus used to force the lance into an extended position. An apparatus providing such force may, for example, be a replaceable spring. In such an application, an object is to maintain consistency of operation throughout the life of the lance device, rather than a portion of the life of one spring.
Another object is to mechanically prevent more than one puncture from occurring.
Another object is to provide a compact hand-held lancing device that is easy to operate. A further object is to encase the lancing device in casings contoured to facilitate gripping the device. Another object is to provide the lancing device with external means for ensuring a consistent perpendicular lancing operation, where such means may, for example, comprise an end cap having a face perpendicular to the lancing motion.
Another object is to provide the lancing device with a flush mounted trigger or other means to reduce protruding parts that may potentially jab a user or break off. Another object is to provide a lancing device that is not prone to chattering and auto-jarring motions during the lancing operation. A further object is to provide a lancing device a reduced number of external moving pieces, such as handles, during the lancing operation.
Another object is to provide a durable, yet inexpensive, lancing device that provides consistent lance punctures over the life of one or more springs, wherein the springs may be easily replace by opening the device.
Other objects and advantages will be apparent to those of skill in the art from the teachings herein.
A drive spring 28 applies force to the frame 12 for moving the rack 14, wherein the pinion 16 is rotated counterclockwise (clockwise in
The fourth and first rack segments 36 and 30 form a distal acute angle 40. Similarly, the second and third rack segments 32 and 34 form a proximal acute angle 42. When the pinion 16 is located at the proximal acute angle 42, the device 10, and the lance holder 24 in particular, is in the fired position 39. Likewise, pinion 16 located at distal acute angle 44 corresponds to the cocked position 37. The fire path comprises a fire-path oblique angle 44. Similarly, the cocking path comprises a cocking-path oblique angle 46.
The frame 12 is moved into the cocked position 37 by any of known conventional methods, such as a pull handle, and is held in the cocked position by an arm or trigger supported by a fulcrum, for example. To reduce the chance that the pinion 16 will be jammed in the rack 14 a plurality of teeth of the rack segments are modified by widening gaps between teeth. In the illustrated embodiment shown in
The lancing device 10 may be provided with guide means for guiding the rack 14 as it moves between cocked position 37 and fired position 39. With reference to
For some applications, the guide track 62 is preferably a parallelogram. Furthermore, the pin 60 may be parallelogram shaped to further stabilize the frame 12 30 due pin 60 interfacing more completely with the guide track 62, e.g., walls of the pin slide along walls of the track, thereby allowing only relative translation while preventing rotation between the pin 60 and the track 62. Depending on the application, the pinion 16 rotates 180 degrees as the pinion 16 moves from the cocked position 37 to the fired position 39 and another 180 degrees in the same direction of rotation (counterclockwise) as the pinion 16 moves from the fired position 39 to the cocked position 37. The pinion pitch diameter is, for some applications, approximately 0.25 inches.
From the foregoing it is apparent that a method in accordance with the invention comprises creating a laceration with a lance. One such method comprises moving a pinion 16 along a predetermined path (30 and 32) which comprises an oblique angle 44. A lance is constrained to move in a linear motion immediately prior to reaching an extended position. Movement of the pinion 16 is coupled to a lance holder 24 such that the lance holder 24 is extended when the pinion 16 reaches a predetermined position 39 on the predetermined path (30 and 32).
Linear motion of the lance as used above, refers to direction (e.g., translation) rather than velocity or acceleration of the lance. Accordingly, although the speed of the lance holder may vary over the life of the spring 28, it is intended that the spring 28, or other conventional force means, move the lance holder 24 to a predetermined depth that does not vary over the life of the spring. Extension of the lance holder 24 beyond the predetermined depth is prevented in the illustrated embodiment because movement of the pinion 16 in further a proximal direction (upward in
By way of example, another method of lancing comprises moving the pinion 16 along the predetermined path (30 and 32) and stopping movement of the pinion 16 at a predetermined position 39 on the predetermined path. Movement of a lance is coupled to movement of the pinion 16. The method further comprises preventing the lance holder 24 from extending beyond a predetermined depth, wherein the lance holder 24 is at the predetermined depth when the pinion 16 is at the predetermined position. For example, the lance holder 24 is in the extended position when the pinion 16 reaches the fired position 39. The lance is thereby consistently extended to the same depth over the life of one or more springs.
The rack release 230 comprises an extension 232 that depresses as it slides 15 over a conforming extension 234 integral with frame 212. The illustrated extensions are relatively small ramps. Depressing release button 236 disengages the rack release 230 by pushing the extension (rack-release ramp) away from frame ramp 234, thereby firing the lance. Release button 236 is returned to a set position by release button foam spring 238.
Frame 212 and lance holder 224 are operatively positioned in upper case 240 and lower case 242. The cases are snap-fitted together, or maintained together by other conventional means. End cap 244 is removable and protects a disposable lance (not shown). The end cap 244 also helps ensure proper lancing depth. The end cap has a face perpendicular to the lancing motion. The user can thereby stabilize the lancing device by placing the end cap face flush against the skin to ensure a perpendicular lancing operation.
While the present invention has been described with reference to one or more particular embodiments, those skilled in the art will recognize that many changes may be made thereto without departing from the spirit and scope of the present invention. Each of these embodiments, and obvious variations thereof, is contemplated as falling within the spirit and scope of the claimed invention, which is set forth in the following claims.
Claims
1. A lancing device for use with a lance, the device comprising:
- a parallelogram-shaped gear rack;
- a pinion rotatably supported in the gear rack, the pinion being rotated in response to the movement of the gear rack;
- a slider-crank system comprising a drive arm coupled to the pinion; and
- a lance holder coupled to the drive arm, wherein rotation of the pinion drives the lance holder in linear motion.
2. The device of claim 1, comprising a drive wheel coupling the drive arm to the pinion.
3. The device of claim 1, further comprising a drive spring positioned to move the lance bolder.
4. The device of claim 3, wherein the parallelogram-shaped rack is positioned between the lance holder and the drive spring.
5. The device of claim 1, wherein the pinion rotates 360° as the lance holder linearly moves from a cocked position to a fired position and back to the cocked position.
6. A lancing device for use with a lance, the device comprising:
- a parallelogram-shaped rack;
- a pinion rotatably supported in the rack, the pinion being rotated in response to the movement of the gear rack:
- a slider-crank system comprising a drive arm coupled to the pinion; and
- a lance holder coupled to the drive arm, wherein rotation of the pinion drives the lance holder in linear motion,
- wherein the parallelogram-shaped rack comprises a proximal acute angle, and a distal acute angle positioned closer to the lance holder than the proximal acute angles, and
- wherein the pinion rotates 180° when moving between the distal acute angle and the proximal acute angle.
7. The device of claim 6, wherein the lance holder moves from a cocked position to a fired position and wherein the lance holder is in the cocked position when the pinion is positioned at the distal acute angle and in the fired position when the pinion is positioned at the proximal acute angle.
8. The device of claim 6, further comprising:
- a first guide pin fixed relative to the parallelogram-shaped rack; and
- a first guide track linearly fixed relative to the pinion, wherein the first guide pin movable interfaces with the first guide track as the parallelogram-shaped rack moves relative to the pinion, whereby movement of the rack is guided.
9. The device of claim 8, further comprising:
- a second guide pin fixed relative to the parallelogram-shaped rack, wherein the rack is positioned between the first and second guide pins; and
- a second guide track fixed relative to the first guide track, wherein the pinion is positioned between the first and second guide tracks and the second guide pin movable interfaces with the second guide track as the parallelogram-shaped rack moves relative to the pinion.
10. The device of claim 9, wherein the first and second guide tracks are parallelogram shaped.
11. The device of claim 8, wherein the first guide track is parallelogram shaped.
12. The device of claim 11, wherein the first guide pin is cylindrically shaped.
13. A lancing device for use with a lance, the device comprising:
- a parallelogram-shaped rack, the rack comprising four segments;
- a pinion rotatably supported in the rack, the pinion being rotated in response to the movement of the rack, the pinion moving between a first acute angle position and a second acute angle position, the pinion comprising teeth;
- a slider-crank system comprising a drive arm coupled to the pinion; and
- a lance holder coupled to the drive arm, wherein rotation of the pinion drives the lance holder in linear motion,
- wherein the rack segments comprise teeth adapted to engage the pinion teeth and at least two teeth on each segment are modified to reduce chances of the pinion jamming at either one of the first and second acute angle positions.
14. A lancing device for use with a lance, the device comprising:
- a frame comprising a parallelogram-shape gear rack, the frame being movably supported;
- a pinion rotatably mounted to interface the gear rack, the pinion being rotated in response to the movement of the gear rack; and
- a lance holder movable between a fired position and a cocked position, wherein movement of the lance holder is in response to rotation of the pinion.
15. The device of claim 14, wherein the lance holder moves from the cocked position to the fired position as the pinion rotates 180°.
16. The device of claim 15, wherein the pinion traverses approximately one-half of the rack as the lance holder moves from the cocked position to the fired position.
17. A lancing device for use with a lance, the device comprising:
- a frame comprising a parallelogram-shape rack, the frame being movably supported;
- a pinion ratably mounted to interface the rack, the pinion being rotated in response to the movement of the gear rack; and
- a lance holder movable between a fired position and a cocked position, wherein movement of the lance holder is in response to the rotation of the pinion.
- wherein the parallelogram-shaped rack comprises a first acute angle and a second acute angle and the pinion is positioned proximate to the first acute angle when the lance holder is in the cooked position and the pinion is positioned proximate to the second acute angle when the lance holder is in the fired position.
18. The device of claim 17, wherein the pinion rotates 180° as the pinion moves from the first acute angle to the second acute angle.
19. A lancing device for use with a lance, the device comprising:
- a frames;
- parallelogram shaped gear rack and pinion means for moving the frame along a predetermined path from a cocked position to a fired position, the gear rack and pinion means comprising one or more rack segments fixed relative to the frame, and a pinion interfacing the one or more rack segments;
- lance holder means for holding and moving the lance in linear motion from a retracted position to a predetermined extended position;
- means for coupling movement of the frame to the lance holder means such that the lance holder moves the lance from the retracted position to the extended position as the frame moves from the cocked position to the fired position along the predetermined path; and
- means for preventing the lance from extending beyond the predetermined extended position.
20. The device of claim 19, further comprising guide means for guiding the frame along the predetermined path.
21. The device of claim 19, further comprising spring means for moving the frame from the cocked position to the fired position.
22. The device of claim 21, further comprising release means for releasing the frame from the cocked position and allowing the spring means to move the frame to the fired position.
23. The device of claim 19, wherein the predetermined path along which the frame moves is non-linear.
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Type: Grant
Filed: Oct 14, 2003
Date of Patent: Dec 5, 2006
Patent Publication Number: 20040127928
Assignee: Bayer Healthcare LLC. (DE)
Inventors: Robert C. Whitson (Elkhart, IN), Norman S. Miller (Lafayette, IN)
Primary Examiner: Thomas Barrett
Assistant Examiner: Christopher D. Prone
Attorney: Jenkens & Gilchrist
Application Number: 10/685,073
International Classification: A61F 17/32 (20060101);